The visually rich and action-packed trailer featured plenty of combat between the massive mechanical soldiers and the enormous alien monsters, who rise from the sea to destroy human cities. In one scene, a human-piloted robot drags a steamship through wet streets with one hand, lifts it, and uses it as a weapon to bash a kaiju’s face.

“One foot of the Jaeger was easily the size of this room,” he said, gesturing to the sports arena. “So we built one foot.”

The Warner Bros. and Legendary Pictures film relies on animation and sets, not motion-capture technology, to achieve that massive scale, he said.

“I think motion capture is great for a certain size, but these things are basically a 25-story-high building walking around. You know, the weight — and I know something about weight myself — the weight makes things moves differently, as my wife would tell you,” he said as the audience laughed at the self-deprecating jest.

Del Toro also talked about his cast, which includes Charlie Hunnam as Raleigh Becket, who along with Rinko Kikuchi’s Mako Mori, pilots one of the robots, as well as Idris Elba, Charlie Day and Ron Perlman as black market organ dealer Hannibal Chow.

“He took the name Hannibal Chow based on his favorite historical figure and his second favorite restaurant in Brooklyn,” Del Toro said. “He’s a black market dealer of the lowest kind. … He sells kaiju powder for ED. It’s 500 bucks a pound.”

Del Toro praised the performance of Charlie Day, saying he was impressed by his acting from “It’s Always Sunny in Philadelphia.”

“I wanted to have a scientist that was a punk rocker,” Del Toro said of Day’s character. “He thinks he’s super hip, but he’s a geek.”

The world in which the epic war takes place was inspired by the scenery and propaganda of World War II, he said.

“We would do a lot of decay, and the places look rusty and used and oxidized,” he said. “We would layer in kaiju warning signs and kaiju refuge signs and pamphlets and flyers.”

It’s an aesthetic that’s evident in the newly-revealed cover art for the previously-announced graphic novel prequel, “Pacific Rim: Tales From Year Zero.”

The cover (check it out in the gallery above) was fully painted by veteran comic artist Alex Ross and features an alien battling a retro-style robot.

“It’s one of the really early robots,” Del Toro said. “It’s a Mark 1. It’s much more rusted and old style.”

The comic, written by Travis Beacham, chronicles the first time the monsters rise from the ocean to attack Earth and features characters who will also appear in the film.

“In the movie, you found out that the kaiju were sent by an alien race that consumes planets,” Del Toro said. “So we wanted to hint at some of the background.”

The comic, illustrated by Sean Chen, Yvel Guichet and Pericles Junior with inks by Steve Bird and Mark McKenna, is due out June 5, a month before the film’s July 12 release date. Plans for a sequel were announced in December.

“Pacific Rim” is Del Toro’s first stint directing since 2008’s “Hellboy II: The Golden Army,” although he has produced several films in the meantime, including “Don’t Be Afraid of the Dark” and “Puss in Boots.” But for Del Toro, making “Pacific Rim” has been a career highlight.

“The most amazing experience I’ve had making a movie, the most harmonious, free, amazing experience was ‘Pacific Rim,'” he said.